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    Subject[PATCH 2/2] dma-debug: Put all hash-chain locks into the same lock class
    Date
    From: Ingo Molnar <mingo@elte.hu>

    Alan Cox reported that lockdep runs out of its stack-trace entries
    with certain configs:

    BUG: MAX_STACK_TRACE_ENTRIES too low

    This happens because there are 1024 hash buckets, each with a
    separate lock. Lockdep puts each lock into a separate lock class and
    tracks them independently.

    But in reality we never take more than one of the buckets, so they
    really belong into a single lock-class. Annotate the has bucket lock
    init accordingly.

    [ Impact: reduce the lockdep footprint of dma-debug ]

    Reported-by: Alan Cox <alan@linux.intel.com>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
    Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
    ---
    lib/dma-debug.c | 2 +-
    1 files changed, 1 insertions(+), 1 deletions(-)

    diff --git a/lib/dma-debug.c b/lib/dma-debug.c
    index a9b6b5c..c9187fe 100644
    --- a/lib/dma-debug.c
    +++ b/lib/dma-debug.c
    @@ -716,7 +716,7 @@ void dma_debug_init(u32 num_entries)

    for (i = 0; i < HASH_SIZE; ++i) {
    INIT_LIST_HEAD(&dma_entry_hash[i].list);
    - dma_entry_hash[i].lock = SPIN_LOCK_UNLOCKED;
    + spin_lock_init(&dma_entry_hash[i].lock);
    }

    if (dma_debug_fs_init() != 0) {
    --
    1.6.3.3



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